Fire dampers are not required in penetrations of shafts where separated by how many hours of fire resistance rated construction?

Fire dampers are designed to prevent the spread of fire and smoke through openings in fire-resistance-rated walls, floors, and ceilings. The correct answer indicates that when the penetrations of shafts are separated by 2 hours of fire-resistance-rated construction, fire dampers are not required.

This aligns with building codes and regulations, which establish that when particular fire-resistance ratings are met, the integrity of the barrier is sufficient to contain fire and smoke for a specified duration without the need for additional protective measures such as dampers. The 2-hour rating indicates that the construction can withstand a fire for that duration, providing adequate time for safety measures to be enacted following a fire incident.

Fire-resistance ratings are crucial for the designed safety of structures because they dictate how long a barrier can hold against fire. The higher the fire-resistance rating, the less likely it is that fire dampers are necessary for the penetrations, leading to reduced complexity and potentially lower costs in construction.